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= Python实现标签云 =

来源：http://sujitpal.blogspot.com/2007/04/building-tag-cloud-with-python.html

{{{
#!python
# !/usr/bin/env python
# -*- coding: utf-8 -*- 
# !/usr/bin/env python
# -*- coding: utf-8 -*- 

import string

def main():
    # get the list of tags and their frequency from input file
    taglist = getTagListSortedByFrequency('/tmp/tag.txt')
    # find max and min frequency
    ranges = getRanges(taglist)
    # write out results to output, tags are written out alphabetically
    # with size indicating the relative frequency of their occurence
    writeCloud(taglist, ranges, 'tags.html')

def getTagListSortedByFrequency(inputfile):
    inputf = open(inputfile, 'r')
    taglist = []

    for line in inputf: #原文中使用readlines，改为直接迭代文件对象，更pythonic
        line = line[:-1]
        (tag, count) = line.split('|')
        taglist.append((tag, int(count)))

    inputf.close()
    # sort tagdict by count
    taglist.sort(lambda x, y: cmp(x[1], y[1]))
    return taglist

def getRanges(taglist):
    mincount = taglist[0][1]
    maxcount = taglist[len(taglist) - 1][1]
    distrib = (maxcount - mincount) / 4
    index = mincount
    ranges = []
    while index <= maxcount:
        range = (index, index + distrib)
        index = index + distrib
        ranges.append(range)
    return ranges

def writeCloud(taglist, ranges, outputfile):
    outputf = open(outputfile, 'w')
    outputf.write("<style type=\"text/css\">\n")
    outputf.write(".smallestTag {font-size: xx-small;}\n")
    outputf.write(".smallTag {font-size: small;}\n")
    outputf.write(".mediumTag {font-size: medium;}\n")
    outputf.write(".largeTag {font-size: large;}\n")
    outputf.write(".largestTag {font-size: xx-large;}\n")
    outputf.write("</style>\n")
    rangeStyle = ['smallesTag', 'smallTag', 'mediumTag', 'largeTag', 'largestTag']
    # resort the tags alphabetically
    taglist.sort(lambda x, y: cmp(x[0], y[0]))
    for tag in taglist:
        rangeIndex = 0
        for range in ranges:
            url = 'http://www.google.com/search?q=' + tag[0].replace(' ', '+') + '+site%3yoursiteurl'
            if tag[1] >= range[0] and tag[1] <= range[1]:
                outputf.write('<span class=\"' + rangeStyle[rangeIndex] + '\"><a href=\"' + url + '\">' + tag[0] + '</a></span>')
                break
            rangeIndex = rangeIndex + 1
    outputf.close()

if __name__ == '__main__':
    main()
}}}